Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Leaf spring design 4
- Thread starter claver
- Start date
-
2
- #2
-
2
- #3
GregLocock
Automotive
That would be a great place to start. It is also fairly easy to design them from scratch, using a spreadsheet and classic beam theory.
However, to get you going, here is the formula for a multileaf spring, from the Bosch Blue Book
Bending stress= 3*length*Force/(width*N*thickness^2)
N is the number of leaves in the middle, n is the number at the end
rate=(2+n/N)*E*N*width*thickness^3/(6*length^3)
This leaf spring is triangular in side view, ie each leaf is a fixed amount shorter than the one above.
The Devil is definitely in the details, which is where the SAE book will help.
Cheers
Greg Locock
However, to get you going, here is the formula for a multileaf spring, from the Bosch Blue Book
Bending stress= 3*length*Force/(width*N*thickness^2)
N is the number of leaves in the middle, n is the number at the end
rate=(2+n/N)*E*N*width*thickness^3/(6*length^3)
This leaf spring is triangular in side view, ie each leaf is a fixed amount shorter than the one above.
The Devil is definitely in the details, which is where the SAE book will help.
Cheers
Greg Locock
- Thread starter
- #4
Hi Greg,
I have had a go at the formula you have shown. Just a few questions ….
If length, width and thickness is in m, Force in Newton’s. N is the number of leaves at the end. i.e. next to the eye … With 8 springs and 2 at the end (1 is the top spring with the eye) The other 6 are then evenly shorter …right ??
The calculated rate is then the movement in m (from the centre of the spring) for each N applied to the spring ??
E = Youngs Modulus for the material used.
Or have I got myself barking up the wrong tree here ….
Appreciate you comments on this …
Jan
I have had a go at the formula you have shown. Just a few questions ….
If length, width and thickness is in m, Force in Newton’s. N is the number of leaves at the end. i.e. next to the eye … With 8 springs and 2 at the end (1 is the top spring with the eye) The other 6 are then evenly shorter …right ??
The calculated rate is then the movement in m (from the centre of the spring) for each N applied to the spring ??
E = Youngs Modulus for the material used.
Or have I got myself barking up the wrong tree here ….
Appreciate you comments on this …
Jan
GregLocock
Automotive
N=8 n=2, everything else you say is correct.
Cheers
Greg Locock
Cheers
Greg Locock
- Thread starter
- #6
NormPeterson
Structural
And I think that the formula assumes a symmetrical spring package with the axle located at the midpoint as seen in side view and defines the length "L" as being from the axle to either eye rather than being the overall length of the spring between the eyes.
Norm
Norm
GregLocock
Automotive
Yes, L is perversely the half length of the spring.
I don't see how you got 2.86, I think you've got an arithmetic error.
I'd use a t of more like .015, and more leaves, for this design.
You probably want 400-2000 N/mm (roughly) as a rate
Cheers
Greg Locock
I don't see how you got 2.86, I think you've got an arithmetic error.
I'd use a t of more like .015, and more leaves, for this design.
You probably want 400-2000 N/mm (roughly) as a rate
Cheers
Greg Locock
- Thread starter
- #10
- Thread starter
- #11
- Status
Similar threads
- Locked
- Question
- Locked
- Question
- Locked
- Question